Michael Bolin
2f3d0b186b
## Why `cargo nextest` was intermittently reporting `LEAK` for `codex-app-server` tests even when assertions passed. This adds noise and flakiness to local/CI signals. Sample output used as the basis of this investigation: ```text LEAK [ 7.578s] ( 149/3663) codex-app-server::all suite::output_schema::send_user_turn_output_schema_is_per_turn_v1 LEAK [ 7.383s] ( 210/3663) codex-app-server::all suite::v2::dynamic_tools::dynamic_tool_call_round_trip_sends_text_content_items_to_model LEAK [ 7.768s] ( 213/3663) codex-app-server::all suite::v2::dynamic_tools::thread_start_injects_dynamic_tools_into_model_requests LEAK [ 8.841s] ( 224/3663) codex-app-server::all suite::v2::output_schema::turn_start_accepts_output_schema_v2 LEAK [ 8.151s] ( 225/3663) codex-app-server::all suite::v2::plan_item::plan_mode_uses_proposed_plan_block_for_plan_item LEAK [ 8.230s] ( 232/3663) codex-app-server::all suite::v2::safety_check_downgrade::openai_model_header_mismatch_emits_model_rerouted_notification_v2 LEAK [ 6.472s] ( 273/3663) codex-app-server::all suite::v2::turn_start::turn_start_accepts_collaboration_mode_override_v2 LEAK [ 6.107s] ( 275/3663) codex-app-server::all suite::v2::turn_start::turn_start_accepts_personality_override_v2 ``` ## How I Reproduced I focused on the suspect tests and ran them under `nextest` stress mode with leak reporting enabled. ```bash cargo nextest run -p codex-app-server -j 2 --no-fail-fast --stress-count 25 --status-level leak --final-status-level fail -E 'test(suite::output_schema::send_user_turn_output_schema_is_per_turn_v1) | test(suite::v2::dynamic_tools::dynamic_tool_call_round_trip_sends_text_content_items_to_model) | test(suite::v2::dynamic_tools::thread_start_injects_dynamic_tools_into_model_requests) | test(suite::v2::output_schema::turn_start_accepts_output_schema_v2) | test(suite::v2::plan_item::plan_mode_uses_proposed_plan_block_for_plan_item) | test(suite::v2::safety_check_downgrade::openai_model_header_mismatch_emits_model_rerouted_notification_v2) | test(suite::v2::turn_start::turn_start_accepts_collaboration_mode_override_v2) | test(suite::v2::turn_start::turn_start_accepts_personality_override_v2)' ``` This reproduced intermittent `LEAK` statuses while tests still passed. ## What Changed In `codex-rs/app-server/tests/common/mcp_process.rs`: - Changed `stdin: ChildStdin` to `stdin: Option<ChildStdin>` so teardown can explicitly close stdin. - In `Drop`, close stdin first to trigger EOF-based graceful shutdown. - Wait briefly for graceful exit. - If still running, fall back to `start_kill()` and the existing bounded `try_wait()` loop. - Updated send-path handling to bail if stdin is already closed. ## Why This Is the Right Fix The leak signal was caused by child-process teardown timing, not test-logic assertion failure. The helper previously relied mostly on force-kill timing in `Drop`; that can race with nextest leak detection. Closing stdin first gives `codex-app-server` a deterministic, graceful shutdown path before force-kill. Keeping the force-kill fallback preserves robustness if graceful shutdown does not complete in time. ## Verification - `cargo test -p codex-app-server` - Re-ran the stress repro above after this change: no `LEAK` statuses observed. - Additional high-signal stress run also showed no leaks: ```bash cargo nextest run -p codex-app-server -j 2 --no-fail-fast --stress-count 100 --status-level leak --final-status-level fail -E 'test(suite::output_schema::send_user_turn_output_schema_is_per_turn_v1) | test(suite::v2::dynamic_tools::dynamic_tool_call_round_trip_sends_text_content_items_to_model)' ```
Codex CLI (Rust Implementation)
We provide Codex CLI as a standalone, native executable to ensure a zero-dependency install.
Installing Codex
Today, the easiest way to install Codex is via npm:
npm i -g @openai/codex
codex
You can also install via Homebrew (brew install --cask codex) or download a platform-specific release directly from our GitHub Releases.
Documentation quickstart
- First run with Codex? Start with
docs/getting-started.md(links to the walkthrough for prompts, keyboard shortcuts, and session management). - Want deeper control? See
docs/config.mdanddocs/install.md.
What's new in the Rust CLI
The Rust implementation is now the maintained Codex CLI and serves as the default experience. It includes a number of features that the legacy TypeScript CLI never supported.
Config
Codex supports a rich set of configuration options. Note that the Rust CLI uses config.toml instead of config.json. See docs/config.md for details.
Model Context Protocol Support
MCP client
Codex CLI functions as an MCP client that allows the Codex CLI and IDE extension to connect to MCP servers on startup. See the configuration documentation for details.
MCP server (experimental)
Codex can be launched as an MCP server by running codex mcp-server. This allows other MCP clients to use Codex as a tool for another agent.
Use the @modelcontextprotocol/inspector to try it out:
npx @modelcontextprotocol/inspector codex mcp-server
Use codex mcp to add/list/get/remove MCP server launchers defined in config.toml, and codex mcp-server to run the MCP server directly.
Notifications
You can enable notifications by configuring a script that is run whenever the agent finishes a turn. The notify documentation includes a detailed example that explains how to get desktop notifications via terminal-notifier on macOS. When Codex detects that it is running under WSL 2 inside Windows Terminal (WT_SESSION is set), the TUI automatically falls back to native Windows toast notifications so approval prompts and completed turns surface even though Windows Terminal does not implement OSC 9.
codex exec to run Codex programmatically/non-interactively
To run Codex non-interactively, run codex exec PROMPT (you can also pass the prompt via stdin) and Codex will work on your task until it decides that it is done and exits. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on.
Use codex exec --ephemeral ... to run without persisting session rollout files to disk.
Experimenting with the Codex Sandbox
To test to see what happens when a command is run under the sandbox provided by Codex, we provide the following subcommands in Codex CLI:
# macOS
codex sandbox macos [--full-auto] [--log-denials] [COMMAND]...
# Linux
codex sandbox linux [--full-auto] [COMMAND]...
# Windows
codex sandbox windows [--full-auto] [COMMAND]...
# Legacy aliases
codex debug seatbelt [--full-auto] [--log-denials] [COMMAND]...
codex debug landlock [--full-auto] [COMMAND]...
Selecting a sandbox policy via --sandbox
The Rust CLI exposes a dedicated --sandbox (-s) flag that lets you pick the sandbox policy without having to reach for the generic -c/--config option:
# Run Codex with the default, read-only sandbox
codex --sandbox read-only
# Allow the agent to write within the current workspace while still blocking network access
codex --sandbox workspace-write
# Danger! Disable sandboxing entirely (only do this if you are already running in a container or other isolated env)
codex --sandbox danger-full-access
The same setting can be persisted in ~/.codex/config.toml via the top-level sandbox_mode = "MODE" key, e.g. sandbox_mode = "workspace-write".
Code Organization
This folder is the root of a Cargo workspace. It contains quite a bit of experimental code, but here are the key crates:
core/contains the business logic for Codex. Ultimately, we hope this to be a library crate that is generally useful for building other Rust/native applications that use Codex.exec/"headless" CLI for use in automation.tui/CLI that launches a fullscreen TUI built with Ratatui.cli/CLI multitool that provides the aforementioned CLIs via subcommands.
If you want to contribute or inspect behavior in detail, start by reading the module-level README.md files under each crate and run the project workspace from the top-level codex-rs directory so shared config, features, and build scripts stay aligned.